4,5-Dibromo-1,2-benzenediol is obtained by reacting catechol with Bromine in CCl4.
Experimental procedure：In a 500mL three neck round bottom flask under nitrogen, equipped with a refluxcondenser, an addition funnel and a gas outlet connected to a bubbler filled with a 10%NaOH aqueous solution, was suspended catechol (136 mmol, 15.0 g, 1 eq.) in CCl4 (150mL). Bromine (272 mmol, 43.5 g, 2 eq.) diluted in CCla(20mL) was added dropwise at 0℃ over 4.5 h. The excess of bromine was neutralized with aqueous NaHSO4 (150mL,40% solution). The mixture was filtrated and the solids were dissolved in CCLa,washed with water and dried in vacuum. The obtained 4,5-dibromocatechol (30.2 g)was then recrystallized from CHCl3 (220 mL) to afford a white crystalline solid (22.5 g,62%).
